Kinetic and molecular properties of Bacillus subtilis IBTC-3 subtilisin

Comp Biochem Physiol B Biochem Mol Biol. 2005 Feb;140(2):321-31. doi: 10.1016/j.cbpc.2004.10.015.

Abstract

Bacillus subtilis IBTC-3 subtilisin was purified by gel filtration on Sephadex G 75 and affinity chromatography on bacitracin-CNBr-Sepharose 4B and characterized. Its molecular mass of 27 kDa was determined by SDS-PAGE, and isoelectric pH of 8.4 by chromatofocusing. FT-Raman and FT-IR spectroscopy studies revealed fragments with alpha-helix and irregular secondary structures within the polypeptide chain. The beta-sheet conformation was observed only in second-derivatives of FT-RS and FT-IR spectra, in the range of the amide II, III, and I bands. Tyr residues were shown to be hydrogen bonded and CSCH(3) groups adopted two conformations (P(H)-T and P(C)-G conformers). Kinetic properties of B. subtilis IBTC-3 subtilisin in hydrolysis of ethyl esters of amino acid derivatives were compared with that of alkaline peptidase from Bacillus alcalophilus PB92. The first enzyme displayed the highest affinity for NAc-Phe-OEt, both in hydrolysis (K(m) of 0.22 mM) and in synthesis (K(m) of 0.85 mM), whereas PB92 peptidase preferred Tyr derivatives (NAc-Tyr-OEt, K(m) of 0.043 and 0.75 mM, respectively). In contrast to the latter enzyme, B. subtilis IBTC-3 subtilisin catalyzed hydrolysis and synthesis of Bz-Arg-OEt.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacillus subtilis / enzymology*
  • Electrophoresis, Polyacrylamide Gel
  • Kinetics
  • Spectroscopy, Fourier Transform Infrared
  • Spectrum Analysis, Raman
  • Subtilisin / chemistry*
  • Subtilisin / metabolism*
  • Subtilisins / chemistry*
  • Subtilisins / metabolism*

Substances

  • Subtilisins
  • IBTC-3 subtilisin, Bacillus subtilis
  • Subtilisin